General thickness and appearance are more 19th century, certainly not in line with most midcentury work. There are some small random bubbles, though not many. It's good quality work, and I'd lean toward someone like Stevens and Williams if I could confirm they used this color combo.

I just put things under a blacklight. The decanter body glows a bit green while the handle/stopper show somewhat orange. I think that's manganese. On the cup, the handle responded, but the body did not, which suggests they are not an original match. Oh well, the go well together now.

Is your response based on the cups or the decanter? As I indicated in the previous message, the cups and decanter are probably not originally a set. Cups are probably later but hard to pin down. As for the decanter, everything I can check about it says latter part of the 19th century. If 20th century then the very first part.

I was going simply by form and color....?? Im in the USA maybe quite different than from your parts. My personal opinion is that it does look like a set, not a marriage?? And it looks very much like glass we find here that is Mid Century modern. Do not find colors like that typical of the 19th century. So You could say jmho I would search makers like Blenko, Pilgrim, Rainbow glass

I'm in the US, currently Indiana with a lot of time in Southeast Ohio and born in West Virginia. I'm fairly familiar with the companies you name, and this isn't anywhere like what they did.

This combination, often in darker shades, was used by several companies in the late 19th century. You may be thinking of some of the frilly items that get called Victorian, which was a poor choice of terms on my part since there really is no such style as Victorian.

Now if I was going to attribute glass like this to a WV company (the location of the companies you mentioned), I would much sooner go with Northwood or Hobbs, but it would still be circa 1885-1900. However, I don't think either of those companies used this color combination.